You have single-quoted arguments inside of a single-quote argument:

"expect -f '$theScript' '$cd' pwd 'find . -name  '*.std*' -s 
           (^^^^^^^^^^) (^^^)     (^^^^^^^^^^^^^^)      (^^^
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so the ' before *.std* is the end of one single-quoted string. Since you have no space there, the shell ends up concatenating all of those bits together and trying to match a very long wildcard. The shell likely ends up passing the following arguments to expect:

0: expect
1: -f
2: $theScript
3: $cd
4: pwd
5: find . -name  *.std* -o -name ULOG.* -mtime +9 -type f -exec rm {} 
+\;
6: pwd
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but only if $theScript and $cd don't contain any ' characters and there were no files that matched the very long wildcard find . -name *.std* -o -name ULOG.* -mtime +9 -type f -exec rm {} ; (since none of the * characters were inside of single quotes as far as the shell was concerned).

You'd be better off skipping the shell for this:

    system( 'expect', '-f', $theScript, $cd, 'pwd',
        "find . -name  '*.std*' -o -name 'ULOG.*' -mtime +9 -type f -e
+xec rm {} ';'",
        "pwd",
    );
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                - tye